Gas discharge type display panel and production method therefor

ABSTRACT

In the manufacture of a gas discharge type display panel, by applying a sealing operation along with an exhausting operation, the sealing glass  14  is broken down by a pressure difference between the inside and outside of the panel, and thus, the clearance gap between the substrates can be controlled as desired. In addition, the gaseous component that is unnecessary for the discharge operation is exhausted by setting the temperature of the amorphous sealing glass to exceed its softening-point and be no more than its working point. In the structure of the gas discharge type display panel, a protruding portion having a radius of curvature between 0.1 mm and 1 mm is formed on the sealing glass to reduce the dispersion in the thickness direction of the sealing glass, or the cross-sectional shape of the sealing glass is made convex both at its inside end part and its outside end part.

BACKGROUND OF THE INVENTION

This invention relates to a gas discharge type display panel, such as aplasma display panel, and a method of manufacture thereof.

The production of a gas discharge type display device, especiallyproduction processes from seal frit formation to sealing and exhausting,is described in “FPD Intelligence” magazine (June, 1998), pages 84through 88, for example. The description at page 86 indicates thenecessity of selecting an exhaust temperature not exceeding thesoftening point of the sealing glass.

Also, in a method of manufacture of a gas discharge type display panel,such as a plasma display panel, it is necessary to exhaust the inside ofthe panel in advance of the inclusion of a discharge gas. To do this, inaddition to the above-mentioned method of exhausting only the inside ofthe panel after the sealing, a method of exhausting the whole of afurnace during the sealing so as to exhaust both the inside and outsideof the panel at one time is also known. One example of such a method isdisclosed in Japanese Patent Prepublication No. 326572/1998.

SUMMARY OF THE INVENTION

In a gas discharge type display panel, such as a plasma display panel,as a sealing glass, a material in paste form including an organicsubstance (binder) as an additive, which facilitates the application ofglass frit, is often used. This organic substance is burned duringcalcination, sealing and exhausting processes and is emitted to theoutside of the panel as a gas. However, a small quantity of the gasunusually remaining within the sealing glass after tip off may appearinside of the panel when the panel is discharged. From the sealingglass, the gas involved at the time of sealing, in addition to the gasassociated with the binder, leaks into the inside of the panel whiledischarging, which may contribute to the lowering of brightness whenlighting the panel over an extended time period. The first object of thepresent invention is to provide a gas discharge type display panel whichproduces a lower amount of discharged gas from the sealing glass whendischarging over an extended time period and less lowering of brightnesswhen lighting the panel over an extended time period.

There are cases in which the cross-sectional shape of the sealing glassdisposed between substrates at both the end face thereof on the internalspace side and the end face on the external side is convex in shape, asshown in FIG. 4(b), and, in contrast, in which the cross-sectional shapeat both end faces is concave, as shown in FIG. 4(c), in which the sizeof the cross-sectional area parallel to the substrates varies widely.The exterior stress and the internal stress due to the difference inthermal expansion between the sealing glass and the distortion of thesubstrates are applied uniformly inside of the sealing glass. Owing tothis, there is a problem in the conventional gas charge type displaypanels in that the portion having a small cross-sectional area,especially for the cross-sectional area of the sealing glass parallel tothe substrates, has a lower strength. The second object of the presentinvention is to provide a gas discharge type display panel having a highreliability in mechanical strength.

In the conventional method of manufacture of gas discharge type displaypanels, such as plasma display panels, though an amorphous glass frit,rather than a crystalline glass frit, is typically used in considerationof the advantages in process temperature margin, the amorphous glass hassuch a characteristic that it is fused when reheated after sealing. Inthe process of manufacturing a gas discharge type display panel, a casemay accidentally occur in which the gas that is unnecessary foreffective discharge remains inside the panel, for example, due to anabsorption of moisture content or carbon dioxide gas on the MgO film ofthe protection layer of the plasma display panel. Though themanufacturing method certainly employs a process for removing thosegaseous impurities by exhausting the inside of the panel at a hightemperature, if the seal frit gets soft at too high a temperature due toinadequate temperature control and leaks accidentally, the displayoperation is disabled. Thus, in case of applying an amorphous glass fritto the seal frit of the gas discharge type display panel, the gastemperature for exhausting in high temperature conditions has beenselected to be no more than the temperature at the softening point ofthe seal frit. On the other hand, in terms of removing the gaseousimpurities efficiently, it is preferable to use as high a temperature aspossible for high-temperature exhaust operations.

As for another exhaust method, there is a method in which, after sealingthe front substrate and the back substrate by fusing and fixing theconventional sealing glass, only the inside of the panel is exhausted ina vacuum along with baking the inside of the panel. In this method, incase the distance between the front substrate and the back substrate isas small as several hundred mm, it could takes several hours to exhaustthe internal gas completely due to high exhaust conductance; and,especially, in case the discharge areas are formed by closed cellsseparated by separation walls, the complete exhausted state can not beestablished.

On the other hand, in a method in which the whole of the furnace isexhausted in a vacuum when sealing, and the inside and outside of thepanel are exhausted simultaneously, it is required to use proceduresincluding steps for exhausting the whole of the furnace itself or to usea vacuum chamber formed to be large enough to enclose the panel atfirst, and then to fill the chamber with a larger quantity of dischargegas than the volume of the inside of the panel, which requires anupsizing of the manufacturing apparatus and reduces its productivity.The third object of the present invention is to provide a gas displaytype display panel and its manufacturing method which makes it possibleto establish a high efficiency in exhaust operations and reduce thegaseous impurities which remain in the final product.

Since the aforementioned methods use a pressurizing clip in hightemperature conditions, such clips should have heat resistingproperties; however, such a clip may be high-priced and may be damagedby repetitive use in the manufacturing process, or degraded for adesignated clip pressure. In addition, for gas discharge type displaypanels, such as plasma display panels, though plural substrates can bemanufactured from a single glass plate, as in the manufacture of liquidcrystal panels, even in trying to form a single plate by sealing themtogether at first and then separate them into plural panels later, sinceit is difficult to apply a uniform load onto the connecting partsbetween the panels in the sealing process, there has been a problem inthat special tools for pressurizing operations are required, leading toa further increase in cost. The fourth object of the present inventionis to provide a manufacturing method which only uses clips for temporaryfixing and protecting against displacement in order to apply pressure insealing the front substrate and the back substrate and which makes itpossible to seal plural panels simultaneously with a high yield rate.

The sealing operations are performed typically in a temperature rangecorresponding to the viscosity between 104 (working point) and 107.65(softening point). The present invention uses a seal frit formed byadding fillers to PbO—B₂O₃ system glasses, and with this seal frit therewas not found any leakage or large scale displacement of the sealingglass toward the inside of the panel, and the sealing glass could bebroken down to a thickness equivalent to the height of the separationwall merely in response to the difference in the pressure between theinside and outside of the panel, without using any special pressurizingclip, even if the inside of the panel is exhausted at a temperatureexceeding the temperature corresponding to the softening point and lessthan the temperature corresponding to the working point. In addition, ithas been found that there are protruding portions having a radius ofcurvature between 0.1 mm and 1 mm, measured from the display surface, onthe sealing glass over its internal space as a whole. The aforementionedfirst embodiment can be attained by allowing the surface glass to haveprotruding portions having a radius of curvature between 0.1 mm and 1mm, measured from the display surface, on the sealing glass over itsinternal space as a whole.

The aforementioned second embodiment of the present invention can beattained by causing the shape of the cross-sectional area of the sealingglass and at both the end face of the internal space side and the endface of the external side to be convex at least at one part of theperiphery of the substrate.

Furthermore, as the exhaust operations are applied to the sealing glasshaving a clearance gap between the separation wall and the frontsubstrate before the sealing glass is broken down, when exhaustoperations are performed in the sealing process, exhaust operations withhigh efficiency can be performed and the resultant concentration ofgaseous impurities can be reduced. With this method, the exhaustoperations can be carried out smoothly for a gas discharge type displaypanel, in which the discharge space formed as cells separated byseparation walls is typically exhausted with more difficulty duringexhausting operations than a gas discharge type display panel having astraight separation wall structure. By using two different kinds ofsealing glasses having different softening points, one sealing glass issealed at a lower temperature at first, which is designed to make thesealing glass having a higher softening point operate as a spacer and toexhaust the existing clearance gap between the separation wall and thefront substrate, and then, heating it to a higher temperature in orderto seal with the sealing glass having a higher softening point, thetemperature profile for sealing and exhausting operations may havehigher freedom with respect to time and temperature, and, consequently,exhausting operations with higher efficiency can be performed easilyduring the temperature rise phase. In addition, even in a case in whichthe exhaust operations are performed after sealing, exhaustingoperations with higher efficiency can be performed by selecting theoperation condition having a temperature range exceeding the softeningpoint and no more than the working point, and, consequently, theresultant concentration of the remaining gaseous impurities can bereduced. The aforementioned third object of the present invention can beattained by exhausting the inside of the panel during the sealingprocess and by applying the exhausting operations in a temperature rangeexceeding the softening point and no more than the working point.

In case of using a sealing glass containing a filler, when the inside ofthe panel is exhausted in the sealing process, the filler is drawnfirmly toward the inside space and the average filler concentration fromthe end face of the internal space side to the range of 100 mm may be10% or more higher than the average filler concentration in the otherpart. In such a case, since the liquidity in the inside space can bereduced by collecting the filler in the inside space when sealing, thesealing glass does not move largely to the inside space even if theexhausting operations at a higher temperature are applied later, and thevolume for the exhaust route can be effectively reserved. In this case,though a problem may unexpectedly arise in that only the thermalexpansion at the inside space becomes lower, since there are manyconcave and convex parts in the inside space in a practical sense, andthus, the distortion due to the difference in the thermal expansionbetween the substrate and the inside space may be relaxed, this does notlead to such a severe problem as cracks and large-scale distortion forthe whole panel.

In case of using V₂O₅—P₂O₅ system glasses having a lower thermalexpansion coefficient without a filler to be added, instead of usingPbO—B₂O₃ system glasses with a filler added as a seal frit, as theliquidity at the high temperature becomes higher, the sealing glass willmove largely to the inside space and may leak accidentally. In order toprevent this problem, a glass layer having a higher heat resistance thanthe sealing glass is formed so as to be adjacent to the end face of theinside space or located within 2 mm from the end face in order to blockthe flow of the sealing glass. This glass layer may be formed by amaterial identical to the material used for the separation wall at thesame time when the separation wall is formed, or it may be formed byadding another seal frit around the inside space.

By exhausting when sealing, due to the pressure difference between theinside and outside of the panel, as described above, the sealing glasscan be broken down to a thickness equivalent to the height of theseparation walls without using pressurizing clips. Also, in a case inwhich two or more gas discharge type display panels are manufacturedfrom a couple of substrates, the parts which can not be sufficientlypressurized by the conventional pressurizing clips may be pressurized byexhausting at the same time as sealing, and thus, since the sealing canbe established with a higher yield rate independently using the layoutmethod of two or more gas discharge type display panels, it is possibleattain the fourth object of the present invention.

In a case in which the seal frit is used for sealing the substrates, dueto a pressure difference between the inside and outside of the panel,the seal frit made of crystalline glass frit (also including fillermaterials conditionally) may not be broken down completely if theexhaust operations are performed before the viscosity of the materialincreases due to crystallization. Thus, since there is such a severetime condition for pressure reduction, it is preferable to use anamorphous glass frit (also including filler materials conditionally) asthe seal frit used for sealing the substrates.

As for the seal frit used for bonding the exhaust tube, by making theshape of the exhaust tube so as to allow the area of the bonding surfacebetween the exhaust tube and the substrate to be large enough, therewill be no leakage problem in the exhaust operations performed at hightemperature even that is using an amorphous glass frit (also includingfiller materials conditionally) identical to the material used forsealing the substrate. However, when “an amorphous glass frit (alsoincluding filler materials conditionally) having higher softening pointis used for bonding the exhaust pipe, and an amorphous glass frit (alsoincluding filler materials) having lower softening point is used forsealing the substrate”, or “a crystalline glass frit (also includingfiller materials conditionally) having higher softening point is usedfor bonding the exhaust pipe, a crystalline glass frit (also includingfiller materials conditionally) having lower softening point is used forsealing the substrate, and then the exhaust operations are applied aftercompleting the crystallization of the crystalline glass and fixing theexhaust tube”, by making the materials used for seal frits for bondingthe exhaust tube have higher heat resistance than the materials forsealing the substrate, there will be no problem of leakage from thebonding part of the exhaust tube independently of the shape of theexhaust tube.

The exhaust tube is typically designed and manufactured so that theexhaust port may be connected to the end side of the bonding part to thesubstrate, and after the exhaust operations have been completed and theinternal gas is completely exchanged, the exhaust pipe near the bondingpart to the substrate may be burned off for sealing. Alternatively, aglass component shaped in the form of a short exhaust pipe is connectedto the substrate, and, without connecting an exhaust port to the glasscomponent individually, a larger exhaust port is connected to thesubstrate and the exhaust operations are applied to the enclosure of theglass component, and then the glass component is heated for burning off.However, in case of using the glass component exclusively for this wayof sealing, the present invention can give an identical effect broughtabout by the same method as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a top plan view and FIG. 1(b) is a cross-sectional viewshowing the shape of the sealing part of the plasma display panel of thefirst embodiment of the present invention.

FIG. 2 is a diagram which shows temperature profiles at the sealing andexhausting operations in the first embodiment.

FIGS. 3(a) to 3(c) are diagrams which illustrate stepwise changes in thepanel formation after the sealing process in the first embodiment.

FIG. 4(a) is a top plan view and FIGS. 4(b) and 4(c) are side sectionalviews showing the shape of the sealing part of a conventional plasmadisplay panel.

FIGS. 5(a) and 5(b) are graphs which show a relationship between thelighting voltage and the time for the exhausting and aging operations,respectively, in the first embodiment.

FIGS. 6(a) and 6(b) are diagrams which show an exhaust route of theplasma display panel.

FIG. 7 is a graph which shows a variation per hour in the brightness inthe prior art and in the first embodiment.

FIGS. 8(a) to 8(d) are diagrams which show temperature profiles at thesealing and exhausting operations in the second embodiment.

FIG. 9 is a side sectional view which shows a shape and a state of thesealing part of the plasma display panel.

FIGS. 10(a) and 10(b) are graphs which show a relationship between thelighting voltage and the time for the exhausting and aging operations,respectively, in the first embodiment.

FIGS. 11(a) and 11(b) are cross-sectional views showing the shape of anexhaust pipe 13.

FIG. 12 is a cross-sectional view of the plasma display panels of thefourth embodiment and the prior art.

FIG. 13 is a graph which shows temperature profiles at the sealing andexhausting operations in the fourth embodiment.

FIG. 14 is a top plan view of the back substrate 2 of the fifthembodiment.

FIG. 15 is a graph which shows temperature profiles at the sealing andexhausting operations in the fifth embodiment.

FIG. 16 is a graph which shows temperature profiles at the sealing andexhausting operations in the sixth embodiment.

FIGS. 17(a) to 17(c) are side sectional views which illustrate stepwisechanges in the panel formation after the sealing process in the sixthembodiment of the present invention.

PREFERRED EMBODIMENT OF THE INVENTION

(Embodiment 1)

A method of manufacture of plasma display panels representing a firstembodiment of the present invention will be described. In thisembodiment, a sealing method is used in which the panel is sealed whilebeing subjected to an exhaust operation, and the sealing glass is brokendown by using the pressure difference between the inside and outside ofthe panel. For comparison, a panel manufactured by the conventionalsealing method in which the panel is pressurized by clips will bestudied as well.

In this embodiment, the pattern for the sealing glass 14 is formed by adispensing method applied to the back substrate 2, and then, the sealfrit is formed by drying and removing the binders. An amorphous glasstype seal frit (390° for softening point, 450° for working point andalso including the filler materials) is used for the sealing glass 14.

Next, the processes performed after the sealing and exhaust operationswill be described. In FIG. 2, a temperature profile for the sealing andexhaust operations is shown. FIG. 2 illustrates the temperature profilesof panels being exhausted during the sealing operation. The sealing andexhaust processes in accordance with the present invention include aheating-up process for increasing the temperature up to the sealingtemperature (450° C.), followed by a first heat insulation process formaintaining the sealing temperature, a cool-down process for initiatingthe exhaust operation after the completion of the first heat insulationprocess and for reducing the temperature down to the degasificationtemperature (430° C.), followed by a second heat insulation process formaintaining the degasification temperature, and finally a cool-downprocess for reducing the temperature down to room temperature. In theconventional method, the sealing is completed from the cool-up processto the heating-down process along with pressurization of the facesubstrate 1 and the back substrate 2, and then, the exhaust operation isinitiated and this is followed by the heat insulation process and thecool-down process.

FIGS. 3(a) to 3(c) show a stepwise change in the panel states in theexhausting operation performed during the sealing operation.

(1) At first, the locations of the front substrate 1 and the backsubstrate 2 prepared by the above-described processes are adjusted sothat the display electrode and bus electrode, both formed at the frontsubstrate 1, and the address electrode 10 formed at the back substrate 2are orthogonal to each other. The clip 17 is provided with a weak clipforce because its purpose is not to break down the sealing glass 14. Anycomponent other than clips may be employed so long as the componentprovides no displacement of the sealing glass. Placing the backsubstrate 2 at the upper side, the exhaust pipe 13, which is coated andburned with amorphous glass type seal frit 15 (including fillermaterials), is fixed above the exhaust hole by an anchor. The compositesubstrates are placed inside a furnace and an exhaust head is coupled tothe exhaust pipe 13.

FIG. 3(a) illustrates a panel configuration in which the panel to beexhausted when sealing is installed in the sealing furnace. For simpleexplanation, only the outline of the front substrate 1 and the backsubstrate 2 is shown, and the illustration of the clips 17 used fortemporarily fixing the panel is also simplified. In addition, the anchorfor fixing the exhaust pipe 13 is not shown.

The temperature is raised up to the sealing temperature of 430° C. FIG.3(b) shows the state of the sealing glass 14 immediately after thetemperature reaches 430° C., as well as the action which occurs in theclearance gap between the front substrate 1 and the back substrate 2.The sealing glass 14 gets soft and contacts the front substrate 1, sothat the air tightness of the periphery of the substrates can bemaintained, but the clearance gap between the substrates does not reachthe height of the separation wall 11 because a pressurizing clip is notbeing used. The seal frit 15 used for bonding the exhaust pipe 13 andthe back substrate 2 is not fully crystallized and stays in a state inwhich its viscosity is low.

(2) After the temperature reaches the sealing temperature of 430° C.,the temperature is kept constant for 30 minutes. During this process,the seal frit 15 completes its crystallization, and the exhaust pipe 13firmly contacts the back substrate 2. In this state, the exhaustoperation is initiated.

(3) The temperature is reduced in parallel with the initiation of theexhaust operation. The pressure inside the panel reaches 10⁻² to 10⁻⁴Torr in one or two minutes after starting the exhaust operation, and thesealing glass 14 is broken down by the pressure difference between theinside and outside of the panel. FIG. 3(c) shows the state of thesealing glass 14 after the break-down thereof is completed and shows theclearance gap between the front substrate 1 and the back substrate 2.

(4) The temperature is kept constant at 350° C. in the process ofreducing the temperature while the exhaust operation continues, and thegas that is unnecessary for discharge operations is extracted. Aftercooling the panel down to room temperature, the discharge gas is ledthrough the exhaust pipe 13 to the discharge space so as to make thepressure reach 300 Torr, and then the exhaust pipe 13 is burned off bylocalized heating, after which the formation of the gas discharge typedisplay apparatus is finished.

FIGS. 1(a) and 1(b) show the finished state of the sealing glass 14between the substrates. FIG. 1(a) shows the sealing glass 14 as seen inthe direction from the back of the display panel, in which its widthextends approximately to 5 mm and protruding parts with a radius ofcurvature between 0.1 mm and 1 mm are observed over the entire perimeterof the discharge space. Though protruding parts of the sealing glass 14having a larger volume, which are often observed when the sealing glass14 beaks down due to the pressurizing clips, extend largely bybreak-down operations and thus those parts seem to be shaped inprotruding parts, their radius of curvature is larger and theirformation process and resultant shape is not different from thesmall-sized protruding parts in this embodiment. In addition, thesmall-sized protruding parts in this embodiment are not formedincidentally, but are formed in such a way that the sealing glass 14 ispulled toward the inside space when it gets soft, and this can beobserved at the dispersed positions over the entire perimeter.

FIG. 1(b) shows the state of the sealing glass 14 as seen in across-section through the panel. The sealing glass 14 is broken down tothe state in which its thickness becomes equal to the height of theseparation wall 11, and the shape of its inside end part is convex withrespect to the discharge space and the shape of its outside end part isconcave. This can be interpreted in the following manner. In case theexhaust operations are applied during the sealing process or at atemperature exceeding the softening point after the sealing process, asthe sealing glass gets soft, the sealing glass is pulled back inside thepanel. However, for the viscosity at a temperature less than the workingpoint, the sealing glass does not leak. Though the sealing glass nearthe substrate is not pulsed so much due to friction between the sealingglass and the substrate, the sealing glass near the center of theclearance gap between the substrates and located at a distance from thesubstrates tends to be pulled back inside the panel. Therefore, theshape of its inside end part is convex with respect to the dischargespace and the shape of its outside end part is concave.

FIGS. 4(a) to 4(c) show the finished state of the sealing glass 14between the substrates formed by the conventional sealing method usingclip pressurization for comparison with this embodiment. FIG. 1(a) showsthe sealing glass 14 as viewed in the direction from the back of thedisplay panel, in which the shape of the sealing glass at the dischargespace side and at the outside is defined by curves and smooth lines,respectively. As for the cross-sectional shape of the sealing glass 14between the substrates, there are the case shown in FIG. 4(b), in whichthe sealing glass has a convex (humpbacked) surface at both the endfacing the internal space and the end facing outside, and the case shownin FIG. 4(c), in which the sealing glass has a concave (doubleenveloping) surface at both ends. In general, the states of the sealingglass 14 as seen in cross-section through the panel formed by thesealing method using conventional clip pressurization can be categorizedinto either one of the status shown in FIGS. 4(b) and 4(c). As thosestates include a part having a small cross-sectional area parallel tothe substrates, they tend to yield to the tensile load developed in thedirection in which the substrates are to be removed. As for the stateshown in FIG. 4(b), since all contact angles of the sealing glass 14with respect to the substrate are 90 degrees or more, this state is veryweak also with respect to sheering stress. In contrast, the state of thesealing glass 14, as seen in cross-section through the panel fabricatedin association with this embodiment, has no dispersion in thecross-sectional area parallel to the substrate as shown in FIG. 4(b),which has a strong property against the tensile load developed in thedirection in which the substrates are to be removed. As for the sheeringstress, since this embodiment includes a portion in which the contactangle of the sealing glass 14 with respect to the substrate is 90degrees or more, this embodiment is not superior to the structure shownin FIG. 4(c), but is stronger than the structure shown in FIG. 4 (b).

Thus, due to the fact that the internal end part is shaped so as to beconvex with respect to the discharge space and the outer end part isshaped so as to be concave with respect to the discharge space, which isfound in the panel fabricated in this embodiment, a gas discharge typedisplay panel can be obtained which has sufficient strength with respectto the stress applied in various directions and provides a higherreliability in mechanical strength. By introducing the inert gas whensealing rather than employing an exhausting operation, the cross-sectionat both the internal space end part and the external end part of thesealing glass 14 can be formed to be convex with respect to the internalspace.

In order to study the effect of the exhausting operation initiated whensealing over the performance of the display panel, two types of panelswere manufactured by varying the parameters Xh shown in FIG. 2 definedfor the duration time for the exhausting operation, after which thelighting voltage was measured. Those panels included a panel accordingto this embodiment in which the exhausting operation was initiated whensealing, and a panel in the reference example in which the exhaustingoperation was initiated after the breaking down of the sealing glass 14.The measurement result is shown in FIG. 5(a). In the example of a plasmadisplay panel, by applying the exhausting operation while maintaining ahigh temperature, the protection layer, the fluorescent material, thewater absorbed in the separation walls and the gaseous impurities likecarbon dioxide gas are removed, and thus, the discharge operation can becarried out at a lower voltage. However, when a designated time periodpasses, the gas absorbed in the protection layer and such is notreleased outside, or it may be absorbed again immediately after it isreleased. For example, in the case of the reference example shown inFIG. 5(a), even if the exhaust operation continues for 6 hours orlonger, the lighting voltage does not change.

In order to establish a stable driving characteristic with a lowervoltage for the gas discharge type display panel, such as a plasmadisplay panel, it is the most preferable to maintain the exhaustingoperation for 6 hours even in this reference example. In thisembodiment, the exhausting operation can be completed within 3.5 hours,and the light voltage can be reduced by 50V approximately. This isbecause a large amount of gaseous impurities are released in a shorterperiod of time owing to the exhaust operation initiated at a hightemperature. This can be explained by referring to FIG. 6(a), whichillustrates the exhaust gas flow routes in the panel. The exhaust gasflow routes are categorized into four groups including the gas flowroute between the separation walls 11, the gas flow route around theseparation walls 11, the exhaust hole itself and the exhaust pipe 13. Instudying the former two categories in which the height of the gas flowroute is at most between 100 mm and 200 mm, all the gas flow coming fromthe flow route between the separation walls 11 is converged into theflow route around the separation walls 11, and the exhaust conductanceof the gas flow route around the separation walls 11 is the lowest in apanel in which the distance between the separation wall 11 and thesealing glass 14 is between 3 and 5 mm. Therefore, the exhaust operationwith higher efficiency can be established by using the wider gas flowroute around the separation wall 11.

In this embodiment, the exhaust operation is performed in the statesshown in FIG. 3(b), and the overall state of the panel during thisoperation is such that the substrate glass is deflected due to theatmospheric pressure, as shown in FIG. 6(b). The back substrate 2 andthe separation wall 11 contact each other at the central part of thepanel, and the clearance gap between them is formed by the sealing glass14 working as a spacer disposed around the periphery. Since this gapdefines a gas flow route around the separation wall 11 as an importantstructure determining the exhaust conductance level, the exhaustconductance can be increased by performing the exhaust operation beforebreaking down the sealing glass 14, as in this embodiment. Thus, thefact that the exhaust time is as short as 3.5 hours and the lightingvoltage is low as shown in FIGS. 5(a) and 5(b) comes from a propertythat allows the gas to be easily exhausted.

In the plasma display panels, the gaseous impurities are spiked out fromthe structure components also by the plasma discharge which occursduring in the lighting in addition to the exhaust operation at hightemperature. By making the best use of this property and continuing thelighting operation in a definite period of time before shipping theproducts, the gaseous impurities which were not released by theextraction operation at high temperature can be extracted from thestructure component in order to light the panel stably with a lowvoltage, which is called aging and has come into wide use. FIG. 5(b)shows the relation between the aging time and the lighting voltagestudied for the panel manufactured with the exhausting time required forthe lighting voltage to converge to a steady value (6 hours for thereference example and 3.5 hours for this embodiment) as shown in FIG.5(a). The aging time in the reference example is required to be as longas 20 hours, but the aging time in this example is only ten hours. Thisresult reflects straightforwardly the difference in the concentration ofthe gaseous impurities before aging between those two cases.

As apparent from the foregoing description, the exhausting operationwith higher efficiency can be performed without leakage at such a hightemperature as not previously experienced, which makes it possible toreduce greatly the overall time for manufacturing the panel, includingthe aging process.

FIG. 7 shows the changes in the relative brightness during dischargeoperations measured for a panel formed by aging for 20 hours afterapplying the exhausting operation for 6 hours as a reference example,and the panel formed by aging for 10 hours after applying the exhaustingoperation according to this embodiment, assuming that the initial whitebrightness is normalized to 100%. The relative brightness in thereference example is reduced by 27% after continuing the dischargeoperation for 10,000 hours, and in contrast, the relative brightness inthis embodiment is reduced by at most 20%. This result shows that, inthe reference example, the inside of the panel is contaminated bygaseous impurities that are released from the sealing glass 14 over anextended time period even if the panel is finished by the aging process.In contrast, in this embodiment, since the sealing glass 14 hasprotruding portions having a radius of curvature between 0.1 mm and 1 mmand, hence, its surface area is larger, the gaseous component can beextracted efficiently from the sealing glass 14 in the exhaustingoperation, and, consequently, the amount of gas developed during thedischarge operation can be reduced. Thus, if the sealing glass 14 isformed so as to have protruding portions having a curvature radiusbetween 0.1 mm and 1 mm as viewed in the direction from the displaypanel along the overall periphery in the internal space of the sealingglass 14, it can be concluded that a decrease in the brightness whilelighting the panel for an extended time period can be avoided. Since thesurface area at the protruding portions having a radius of curvatureless than 0.1 mm or exceeding 1 mm does not change too much, itsbrightness may undesirably decrease as much as the brightness for thereference example does. In addition, as apparent from the description ofthe manufacturing method for the panels, it is possible to manufacturethe gas discharge type display panel without using pressurizing clips.In a method in which only four clips for positioning as shown in FIG. 3are used for temporarily fixing the panel, a couple of 42-inch AC-typeplasma display panels formed together so as to be adjacent to each otheron a common large-sized substrate are successfully sealed. Since theboundary portion between two panels can not be fully pressurized only bythe use of conventional clips 16 for pressurizing the frit, and, hence,the resultant display panel is easily broken due to camber ordistortion, the yield rate for sealing is as low as 10% or less, andcolor mixture is found in the portions to which the pressurization wasnot fully applied. Thus, we could not obtain 42-inch sized panelssatisfying practical performance requirements. In contrast, by using thesealing method of this embodiment, we could obtain panels with a yieldrate of more than 90% providing the same satisfactory performance levelas the panels formed by sealing individual panels separately. In case ofapplying the sealing method of this embodiment, plural large-sizedpanels can be sealed all at once with higher yield rate, which is validfor achieving a higher productivity and reduction of the manufacturingcost. As for the bonding method for the exhaust pipe 13, there is amethod in which the upper face of the flared part of the exhaust pipe 13and the back glass substrate are bonded by the sealing glass 14 (pasteor preform), which is used for mass-production and has become popular.It may be possible to apply this method to this case if some problems onleakage occur, while a reduction of the pressure in the sealingoperation could be solved by using an exhaust pipe 13 that is shaped soas to enable a firm contact between the exhaust pipe 13 and the backface substrate 2 and such.

(Embodiment 2)

In the second embodiment of the present invention, a plasma displaypanel is formed by using the different exhaust gas temperature from thefirst embodiment. FIGS. 8(a) to 8(d) shows the temperature profile forthe sealing and exhausting processes.

Another plasma display panel is formed by a procedure which includesinitiating the exhausting operation after holding the temperature at430° C. for 30 minutes and then cooling the panel down to roomtemperature without maintaining the temperature constant while reducingthe temperature. The cross section of the resultant plasma display panelas seen in the direction perpendicular to the back side substrate 2 isthen observed. FIG. 9 illustrates diagrammatically the state of thesealing glass 14.

For the panel formed at 450° C. among the panels formed by varying theexhaust gas temperature, the viscosity of the sealing glass 14 isreduced too much and a leakage is formed in the glass for sealing thesubstrate. In case of sealing the substrate with amorphous glass, thisis not preferable because the leakage may occur when exhausting the gasat a temperature higher than the working point. There is no leakage fora panel formed with a temperature of 455° C. at the same temperaturelevel as above. This can be interpreted by considering the specialdistribution of the filler 12. The filler is distributed uniformly incross section as shown in FIG. 4(b) to which the conventional sealingmethod is applied. However, in the case of this embodiment in which theexhaust operation is applied to the sealing glass 14 having a lowerviscosity, that is, at the sealing temperature, the filler 12 is pulledtoward the discharge space, as shown in FIG. 9, and then the fillerconcentration at the discharge space becomes higher. The liquidity atthe discharge space herewith decreases, and then the leakage is blocked.Consequently, the exhaust operation can be performed even at therelatively higher temperature of 445° C., near the working point. Thefiller distribution state is quantitatively shown in FIG. 9, in whichthe average filler concentration at the portion extending in by 100 μmfrom the end part facing the discharge space is 10% or more higher thanthe other portions. Though the extreme concentration of the filler atany part makes its thermal expansion smaller and may unfavorably causecracks and/or distortion due to the difference in the thermal expansionbetween this part and the substrate, there is no problem in fact becausethe distortion can be released by the protruding portions formed asshown in FIG. 1.

Exceptionally, if the extreme concentration of the filler occurs overthe portions extending in by more than 100 m, this is unfavorablebecause cracks and/or distortion may occur due to the difference in thethermal expansion between those portions and the substrate.

If the increase in the average concentration of the filler at theportion extending in by 100 m from the end part facing the dischargespace is 10% or less, the effect given to the liquidity of the sealingglass 14 is small, and the sealing glass 14 moves toward the insidespace at the relatively higher temperature near the working point. Thus,as this makes the exhaust route narrower, it is preferable to controlthe increase in the average concentration of the filler within 10%.

FIG. 10(a) shows the result of studying the lighting voltage by changingthe exhaust time denoted by Xh, as shown in FIG. 2. FIG. 10(b) shows therelation between the aging time and the lighting voltage. FIG. 10 alsoincludes the result for the case of an exhausting operation at 350° C.,which was described with reference to the first embodiment. As shown inFIG. 10(a), the longer the exhausting operation continues at a highertemperature, the more the concentration of the remaining gaseousimpurities is reduced and the lower the lighting voltage can bemaintained. As for the exhausting time, though the exhaustingconductance of the panel is not high when the temperature is keptconstant after breaking down of the sealing glass 14, the requiredexhausting time can be made shorter at the higher temperature becausethe gaseous impurities are removed more quickly at the highertemperature. It is believed to be apparent that no leakage occurs byadjusting the exhausting time, even if a temperature higher than thesoftening point is maintained for 9 hours.

FIG. 10(b) shows that the aging operation can be performed in a shorterperiod of time if the exhausting operation is applied at a highertemperature, and that the lighting voltage can be made lower. Thisreflects the fact that the concentration of the remaining gaseousimpurities for the panel, in which the exhausting operation is appliedat a higher temperature, reaches a lower level before the agingoperation begins, and that the amount of the gaseous impurities to beremoved during the aging operation can be reduced. As described above,what we can obtain is a gas discharge type display panel in which theexhausting operation can be applied in a highly efficient way byexhausting the panel at a higher temperature and in which theconcentration of the remaining gaseous impurities can be made lower.

(Embodiment 3)

In the third embodiment of the present invention, a plasma display panelis manufactured by using a crystalline glass frit (with the softeningpoint at 390° C., the crystallization peak temperature at 430° C. and afiller included) for the sealing glass 14 and an amorphous glass frit(with the softening point at 390° C., the working point at 430° C. and afiller included) for the seal frit bonding between the exhaust pipe 13and the back substrate 2, and by using an exhaust pipe 13 having asectional form as shown in FIG. 11(a) or FIG. 11(b). This manufacturingmethod is the same as that of embodiment 1, and it uses two temperatureprofiles of the type shown in FIG. 2, including the case (a) in whichthe first heat reserving process continues for 5 minutes and the secondheat reserving process continues for 3.5 hours, and the case (b) inwhich the first heat reserving process continues for 10 minutes and thesecond heat reserving process continues for 3.5 hours.

The exhausting process can be applied with no problem by using anexhaust pipe having a larger connecting area as shown in FIG. 11(b).Even with the exhaust pipe having a smaller connecting area as shown inFIG. 11(a), the exhausting process can be applied properly by usingcrystalline glass for sealing the exhaust pipe 13, as in the embodiments1 and 2, and using amorphous glass for sealing the substrates. Thismeans that if the glass material used for sealing the exhaust pipe 13has a heat resistance higher than the sealing glass 14 for thesubstrates, the viscosity of the glass material for sealing the exhaustpipe 13 is maintained to be a certain level, and no leakage occurs evenif the viscosity of the sealing glass 14 for the substrates mightdecrease at the sealing temperature. In case both of those glassmaterials have an identical viscosity, leakage may occur if the bondingarea between the exhaust pipe 13 and the substrates is not large enough.No matter what shape is used for the exhaust pipe 13, materials withhigher heat resistance are preferably used for the glass for sealing theexhaust pipe 13, rather than for the sealing glass 14 for thesubstrates. Though it is possible to use amorphous glass materials forboth in order to define a difference in their characteristictemperature, too large a difference in their characteristic temperaturecan not be defined, because those sealing glasses are requiredultimately to be sealed, which leads to a difficulty in selecting theglass material. By using a crystalline glass for sealing the exhaustpipe 13 and using an amorphous glass for sealing the substrates, it willbe appreciated that their characteristic temperature could not belimited to each other, and that they can be heated up to a temperaturehigher than the sealing temperature after sealing, which concludes thefact that this combination of glass materials is most preferable.

A plasma display panel was formed at the above-mentioned two temperatureprofiles, and, by using the exhaust pipe 13 as shown in FIG. 11(b), andthe thickness of the sealing glass 14 after the sealing operation wasmeasured and evaluated. It was found that the panel (a) broke down tothe height approximately equivalent to the height of the separation wall11, and that the panel (b) did not fully break down. This shows that thesealing glass 14 gets hard as crystallization proceeds to a certaindegree and that it can not be fully broken down to a desired height. Asin this embodiment, by using amorphous glass material for the sealingglass 14, the freedom in the temperature profiles can be advantageouslyenhanced.

(Embodiment 4)

In the fourth embodiment of the present invention, a plasma displaypanel is manufactured by using a crystalline glass frit (made withV₂O₅—P₂O₅ system, and having a softening point at 390° C., acrystallization peak temperature at 430° C. and a filler included) forthe sealing glass 14 and an amorphous glass frit (made with PbO—B₂O₃system and having a softening point at 390° C., a crystallization peaktemperature at 430° C. and a filler included) for the seal frit bondingbetween the exhaust pipe 13 and the back substrate 2. As shown in FIG.12, this panel has an additional separation wall 18 with 1 mm widthalong the overall periphery inside (within 2 mm) of the sealing glass14. The fabrication method for this panel is almost the same as thepanel in the first embodiment except for the addition of the separationwall 18, and the temperature profile used for the sealing and exhaustingprocesses is shown in FIG. 13.

As a result, the gas inside the panel having the structure shown in FIG.12 can be fully exhausted. This is because the sealing glass can beblocked by the separation wall 18 when the sealing glass is pulledinside the discharge space by the exhausting operation, and thus, thewidth of the sealing glass can be made uniform and the occurrence of theleakage path can be prevented. This separation wall 18 gives such aneffect that, even if the protruding portion formed at the dischargespace by the exhausting operation is removed by the exhausting operationfurther continued, this protruding portion will not extend into theinside of the discharge space and block the exhausting route, and willnot remain between the separation wall 18 and the front substrate 1.Although the separation wall 18 is formed inside the sealing glass 14 inthis embodiment, the same effect can be obtained by forming a sealingglass having a higher softening point as a “levee” inside the sealingglass 14.

(Embodiment 5)

In the fifth embodiment of the present invention, a plasma display panelis manufactured by forming separation walls 11 extending in the verticaland horizontal directions, as shown in FIG. 14, having the same materialstructure as the first embodiment. The manufacturing method for thefront substrate 1 and the back substrate 2 and the number of pixels ofthe panel are the same as those in the first embodiment. Only thesealing and exhausting processes for this embodiment will be describedbelow. The temperature profile used for the sealing and exhaustingprocesses is shown in FIG. 15.

(1) At first, the substrates are aligned and fixed temporarily and theexhaust tube 13 is fixed in the same manner as the first embodiment.Therefor, the composite substrates are installed in the furnace and theexhaust head is connected to the exhaust pipe 13. The temperature isincreased up to the sealing temperature of 430° C. in thisconfiguration. Though the sealing glass 14 gets soft and contacts thefront substrate 1 and the periphery of the substrate is sealedhermetically, the clearance gap between the substrates does not reachthe height of the separation wall 11 because pressurization clips arenot used. On the other hand, the seal frit 15 used for bonding theexhaust tube 13 and crystallization in the back glass substrate is notfully developed at this step, and its viscosity remains low.

(2) After the sealing temperature reaches 430° C., this temperature ismaintained for 30 minutes. During this period, the seal frit 15establishes its crystallization and the exhaust pipe 13 is bonded firmlyto the back substrate 2. The temperature is then reduced to 400° C. inthis state.

(3) After the temperature reaches 400° C., the exhausting operation isinitiated. The sealing glass 14 stays in such a state that it has ahigher viscosity and is less apt to be broken down than at thetemperature of 430° C. Thus, the exhausting operation is applied in astate in which the clearance gap between the front substrate 1 and theback substrate 2 is large. As the exhausting operation for the centerpart of the panel can not be performed efficiently due to the deflectionof the substrate glass, as shown in FIG. 6(b), the exhausting operationis applied again after introducing nitrogen gas in the process, fixingthe deflection and thus facilitating the removal of the gaseousimpurities.

The temperature is raised to 430° C. while continuing the exhaustingoperation after 3 hours has passed since the beginning of the exhaustingoperation.

(4) Along with the increase in the temperature, the sealing glass 14gets soft and is broken down due to the pressure difference between theinside and outside of the panel. After completing the breaking-down ofthe panel, Ne gas including Xe gas by 3% volume at room temperature isintroduced into the discharge space through the exhaust pipe 13 at 700Torr so that its pressure may reach 300 Torr, and the temperature isreduced down to the room temperature. After cooling down, the exhaustpipe 13 is burned off by local heating, and finally, production of a gasdischarge type display device is completed.

Since the exhausting operation is applied after breaking down thesealing glass in the conventional panel manufacturing method, a gasdischarge type display panel in which the discharge space is separatedinto isolated cells by the separation walls 11, as shown in FIG. 14, cannot be exhausted completely. In this embodiment, since the exhaustingoperation can be applied in a state in which the clearance gap betweenthe front substrate 1 and the back substrate 2 is kept large enough, andthe removal of gaseous impurities remaining in the internal space can befacilitated by introducing inert gas such as nitrogen gas, theexhausting operation and the removal of the gaseous impurities can beperformed with high efficiency.

The cell structure shown in FIG. 14 contributes to an increase in theeffective area for applying fluorescent materials, and thus, abrightness of 500 cd/m2 can be attained in comparison with a brightness350 cd/m2 in the cell structure shown in FIG. 6(a).

(Embodiment 6)

In the sixth embodiment of the present invention, in a manner similar tothat of the fifth embodiment, a plasma display panel is manufactured byforming separation walls 11 extending in a vertical and horizontaldirections, as shown in FIG. 14, and sealing the substrates doubly withtwo kinds of sealing glass having an individual softening point that aredifferent from each other. As for the sealing glass outside, what isuses is a low softening-point amorphous seal frit 20, which has asoftening point at 350° C. and the working point 410° C. As for thesealing glass inside, what is used is a high softening-point amorphousseal frit 19, which has the softening point at 390° C. and the workingpoint 450° C. A crystalline glass frit 15 has a softening point at 350°C. and a crystallization peak temperature at 400° C. for bonding betweenthe exhaust pipe and the substrate. Those seal frits include fillermaterials.

The method of manufacture of the front substrate 1 and the backsubstrate 2 and the number of pixels are the same as those in the firstembodiment, except that the seal frits are formed doubly. The sealingand exhausting operations will be described below. The temperatureprofile used in the sealing and exhausting operations is shown in FIG.16. FIGS. 17(a) to 17(c) show the stepwise change in the state of thepanel that is sealed in two steps.

(1) At first, the substrates are aligned and fixed temporarily and theexhaust tube 13 is fixed in the same manner as the first embodiment.Then, the composite substrates are installed in a furnace and theexhaust head is connected to the exhaust pipe 13. The temperature isincreased up to the sealing temperature of 350° C. in thisconfiguration. The crystalline glass frit used for bonding the exhaustpipe 13 and the back glass substrate stays in a state in which itsviscosity is low.

(2) After the sealing temperature reaches 350° C., this temperature ismaintained for 30 minutes. The state at this step is shown in FIG.17(a). The low softening-point seal frit 20 gets soft and contacts thefront substrate 1. Although the periphery of the substrate is sealedtightly, the clearance gap between the substrates does not reach theheight of the separation wall 11 because no pressurization clip is used.While keeping the temperature constant for 30 minutes, the crystallineglass 15 experiences a reduction of the grain size of the glass, afixation with the substrate glass and a slight crystallization, and sothe exhaust pipe 13 is fixed firmly to the back glass substrate. Theexhausting operation (exhausting roughly) is initiated at this step.

(3) In the process of increasing the temperature up to 430° C., althoughthe low softening-point seal frit 20 is broken down, the highsoftening-point seal frit 19 does not get very soft and prevents thesubstrates from contacting firmly to each other by acting as a spacer,as shown in FIG. 17(b). On the other hand, the crystalline glass usedfor bonding the exhaust pipe 13 gradually develops its crystallization,and thus, the bonding between the exhaust pipe 13 and the back glass isfirmly established.

(4) As the temperature reaches 430° C., the high softening-point sealfrit 19 begins to get soft and contacts the front substrate 1, and thesealing of the panel can be established by the high softening-point sealfrit 19 itself. The exhausting operation is further continued up to ahigher vacuum at this step.

(5) In the process of maintaining the temperature constantly at 430° C.,both the high softening-point seal frit 19 and the low softening-pointseal frit 20 are broken down by the pressure difference between theinside and outside of the panel. The state at this step is shown in FIG.17(c). After cooling down to the room temperature, a discharge gas isintroduced into the discharge space through the exhaust pipe 13 so thatits pressure may reach 300 Torr, and the exhaust pipe 13 is burned offby local heating, whereby production of a gas discharge type displaydevice is completed.

Although there may occur a leakage from the seal frit 15 used forbonding the exhaust pipe 13 with the exhausting operation at 350° C.,the exhausting operation can be applied successfully by keeping itsinternal pressure at a low degree of vacuum. In case a single kind ofseal frit is used as in the first embodiment, it is difficult todetermine the exhausting temperature properly and have a higherflexibility in selecting the temperature, because it is desirable toapply the exhausting operation without making the seal frit get soft ata higher temperature. In this embodiment, depending on the combinationof characteristic temperatures for two or more kinds of seal frits,various temperature profiles can be developed. In this embodiment, sincethe exhausting operation can be initiated even during the process ofincreasing the temperature, and the exhausting operation can continue atthe sealing temperature for the high softening-point seal frit, theexhausting operation can be applied with extremely high efficiency.

As shown in FIG. 10(b), though the aging operation is requiredapproximately for 6 hours even by applying the exhausting operation at430° C. for the single-layered sealing configuration, no difference isformed in the lighting voltage after applying the aging operation inthis embodiment, which reflects the fact that the concentration of thegaseous impurities in the panel is low. In the sealing and exhaustingmethod using two kinds of seal frits, as in this embodiment, either ofthe high softening-point glass and the low softening-point glass may bepositioned inside, and the multiple sealing 1 configuration maycontribute to no further extension of its essential effect.

It is possible in the shortest time and with higher operability tomanufacture a plasma display panel having a high mechanical strength anda high reliability, and which is able to be driven with a lower voltage,providing a higher brightness and which has a large dimension.

1. A manufacturing method for a gas discharge type display panel inwhich a couple of substrates are arranged to be facing to each other, asurrounding area of said couple of substrates is sealed by a sealingglass, and an inside space is used as a discharge space by sealing adischarge gas in an internal space, wherein by exhausting said insidespace when sealing, said sealing glass is made broken down and aclearance gap between said substrates is controlled to be as desired. 2.A manufacturing method for a gas discharge type display panel in claim1, wherein an amorphous glass or an amorphous glass including a fillerare used for sealing a substrate.
 3. A manufacturing method for a gasdischarge type display panel in claim 1, wherein a supply and exhaustpipe is formed on an outside surface of said substrate by using a glassmaterial having a heat resistance higher than said substrate sealingglass.
 4. A manufacturing method for a gas discharge type display panelin which a couple of substrates are arranged to be facing to each other,a surrounding area of said couple of substrates is sealed by anamorphous sealing glass, and an inside space is used as a dischargespace by sealing a discharge gas in an internal space, wherein a gasunnecessary for a discharge operation is exhausted from said insidespace under a condition that said amorphous sealing glass is located ina temperature range exceeding its softening point and no more than itsworking point.
 5. A manufacturing method for a gas discharge typedisplay panel in which a couple of substrates are arranged to be facingto each other, a surrounding area of said couple of substrates is sealedby a sealing glasses, and an inside space is used as a discharge spaceby sealing a discharge gas in an internal space, wherein saidsurrounding area of said couple of substrates is sealed at least doublyby said sealing glasses each having an individual softening pointdifferent from each other, one of said sealing glasses having oneindividual softening point sealing said surrounding area, and another ofsaid sealing glasses having another individual softening point anddisposed adjacent to and substantially parallel with said one of saidsealing glasses so as to individually effect sealing of at least thesame said surrounding area.
 6. A manufacturing method for a gasdischarge type display panel in which a couple of substrates arearranged to be facing to each other, a surrounding area of said coupleof substrates is sealed by a sealing glass, and an inside space is usedas a discharge space by sealing a discharge gas in an internal space,wherein a protruding portion having a curvature radius between 0.1 mmand 1 mm is formed on an overall periphery of said sealing glass at itsinside space.
 7. A manufacturing method for a gas discharge type displaypanel in which a couple of substrates are arranged to be facing to eachother, a surrounding area of said couple of substrates is sealed by asealing glass, and an inside space is used as a discharge space bysealing a discharge gas in an internal space, wherein at least at oneportion of said surrounding area of said couple of substrates, across-section of said sealing glass viewed vertically to a substrate ofsaid couple of substrates is shaped so as to be convex with respect tosaid inside space at both its inside space end part and its outside endpart.
 8. A manufacturing method according to claim 7, wherein a gasunnecessary for a discharge operation is exhausted from said insidespace if a state of said sealing glass is located in a temperature rangeexceeding its softening point and no more than its working point.
 9. Amanufacturing method according to claim 7, wherein at least at oneportion of a surrounding area of said substrate, a concentration fillerat an inside space end part of said sealing glass is larger than that inother portions.
 10. A manufacturing method according to claim 7, whereina glass layer having a heat resistance higher than said sealing glass isformed so as to be adjacent to an inside space and part of said sealingglass or within 2 mm from an end part.
 11. A manufacturing methodaccording to claim 7, wherein another sealing glass is provided so thatsaid couple of substrates are sealed at least doubly by said sealingglass and another sealing glass, each having an individual softeningpoint different from each other.
 12. A manufacturing method according toclaim 7, wherein by exhausting said inside space when sealing, saidsealing glass is made broken down and a clearance gap between saidsubstrates is controlled to be as desired.
 13. A manufacturing methodfor a gas discharge type display panel in which a couple of substratesare arranged to be facing to each other, a surrounding area of saidcouple of substrates is sealed by a sealing glass, and an inside spaceis used as a discharge space by sealing a discharge gas in an internalspace, wherein at least at one portion of said surrounding area of saidcouple of substrates, a concentration of filler at an inside space endpart of said sealing glass is larger than that in other portions.
 14. Amanufacturing method for a gas discharge type display panel in which acouple of substrates are arranged to be facing to each other, asurrounding area of said couple of substrates is sealed by a sealingglass, and an inside space is used as a discharge space by sealing adischarge gas in an internal space, wherein a glass layer having a heatresistance higher than said sealing glass is formed over an entireperiphery of said inside space so as to be adjacent to an inside spaceend part of said sealing glass or within 2 mm from the inside space endpart.